This invention relates to continuously-variable-ratio transmissions of the toroidal race rolling traction type. It relates especially to control of the variator, that is to say the ratio-varying unit, of such a transmission. Such units have been described in detail in various published patent specifications, such as GB-1296827, which will be described in more detail later. From this and other specifications it is known to provide a ratio-varying unit comprising an input disc and an output disc and rollers to transmit drive between them and a control member disposed within the unit (e.g. within the casing thereof) operable to vary the attitude of the rollers in unison and so vary the transmitted ratio.
In sophisticated transmissions using variators of the toroidal race type, it is known for the said member to be controlled by a lever which is precisely located at all times by a mechanism capable of working within close limits of accuracy. Examples of hydraulic mechanisms for this purpose are described in detail in GB-2023753-B and GB-2100372-B. The present invention, however, relates primarily to less sophisticated and expensive transmissions, and for the need to provide for the control member an operating mechanism that is simple and versatile and is operationally more effective than for the operator simply to hold the end of a lever.